Fluoride-containing compositions, such as solutions or gels, have been known and have been employed for use in professional topical applications to teeth in the oral cavity. Such topical compositions have been employed since studies have indicated that, when fluoride penetrates into tooth enamel from a topical application, the tooth enamel becomes more caries-resistant. It has been demonstrated that ammonium fluoride has been shown to be an effective topical fluoride agent in vitro, as well as in vivo, with respect to the amount of fluoride that penetrates into the tooth enamel and which becomes firmly bound to the tooth enamel (see V. Caslavska, et al, Response of Human Enamel to Topical Application of Ammonium Fluoride, Archs. Oral Biology, Vol. 16, pp. 1173-1180, 1971, and Paul F. DePaola, High-Concentration Fluoride Preparations and Use for Preventing Caries, U.S. Pat. No. 4,078,053, issued Mar. 7, 1978).
Typical fluoride solutions and gels that are available for use in professional topical applications are set forth in Fluorides: An Update for Dental Practice, American Academy of Pedodontics, 1976. One such solution is a neutral pH 7 sodium fluoride solution. This solution is applied by a technique that calls for a preapplication pumice prophylaxis, interproximal flossing and drying of the tooth surface with compressed air. A solution of neutral 2% sodium fluoride is applied with cotton rolls and allowed to dry for 3 to 4 minutes. Four of these applications are necessary over a one-month period, which means that one-week intervals are usually the protocol. However, the prophylaxis technique is required only for the first of the four visits. This procedure is best used at ages three, seven, ten and thirteen, to coincide with the eruption of the deciduous teeth and the young permanent teeth.
Another solution used is a 1.23% acidulated orthophosphate-fluoride pH 3.2 preparation applied semiannually. Pumice prophylaxis, flossing and drying of the teeth are also required with this treatment. The solution is then applied with cotton applications for 4 minutes, making sure that the applicators remain continuously during the four-minute period. The solution is then allowed to dry. The patient is permitted to expectorate, but cannot eat, drink or rinse for at least 30 minutes post-application.
A third preparation is an acidulated phosphate fluoride (APF)-stannous fluoride combination solution which requires application of the APF for 2 minutes, followed by a two-minute application of a 0.5% stannous fluoride solution. A 10% stannous fluoride solution, applied to air-dried teeth for 15 to 30 seconds, is another possible alternative.
With respect to gels, a widely used preparation is an APF gel. The protocol for use is the same as that for the APF solution, except that the preparation is applied with cotton tips or via a tray as a gel.
The use of a fluoride-containing solution or a gel provides certain problems and benefits on topical application. The fluoride-containing solution, being less viscous than a gel, tends to enter more readily into the narrow spaces between the teeth and to penetrate more deeply into sulci in a given period of time than gel-type compositions. However, such fluoride-containing solutions, by being less viscous, tend to be washed away from the tooth surfaces and crevices much easier than gels. The employment of gels, with viscosity-increasing agents, provides for retention of the fluoride-containing gel on the enamel surfaces for longer periods of time than fluoride solutions. However, viscosity-increasing agents do not facilitate penetration of such gels into narrow enamel pores and, thus, may reduce the amount of fluoride uptake by the dental enamel, and, where the gel is very viscous, the longer it takes for the fluoride to be released from the gel preparation. Despite the long release time, the fact that the gel stays longer on the tooth surface allows more reaction time with the enamel, which often compensates for the slower release time of the fluoride. It has been reported that the clinical effectiveness of solutions and gels of the same compound is quite similar (see Brudevold, F., Naujoks, R., 1978, Caries-Preventive Fluoride Treatment of the Individual, Caries Res. 12 (supp. 1): 52-64, and Wei, S.H.Y., 1973, Fluoride Uptake by Enamel from Topical Solutions and Gels: an in vitro Study, J. Dent. Chil. 40: 299-302).
Thus, it would be desirable to provide for a composition, method and technique which would have the advantages of both fluoride-containing solutions and gels, without the disadvantages of either.